The present invention generally relates to material movement in a manufacturing environment and, more particularly, to systems and methods for managing material movement and material to be processed in a semiconductor fabrication facility.
Conventional manufacturing plants and processes have the task of moving material around and through the manufacturing process. Whether it is material to be used in making a product or the material itself that will be processed and turned into a product, there is a need to track the material and to control the manufacturing operation being applied to it. Further, if conditions where to change that would alter the normal schedule and processing path, it would be very difficult today to integrate such changes into the current manufacturing operation without substantial manual intervention in the process. This is further complicated when dealing with a semiconductor fabrication environment as described below.
A conventional semiconductor fabrication plant typically includes multiple fabrication areas or bays interconnected by a path, such as a conveyor belt. Each bay generally includes the requisite fabrication tools (interconnected by a subpath) to process semiconductor wafers for a particular purpose, such as photolithography, chemical-mechanical polishing, or chemical vapor deposition. Material stockers or stocking tools generally are located about the plant and store semiconductor wafers waiting to be processed. The wafers are typically stored in containers, such as cassettes, each of which can hold up to 25 wafers. The cassettes are then stored in carriers that facilitate movement throughout the plant. The carriers can move material in lots, primarily between stocking locations, such as production wafers, test wafers, or empty cassettes if necessary to ensure that the process is moving smoothly.
A material stocker typically services two or more bays and can hold hundreds of cassettes. While not shown, the semiconductor fabrication plant, including the bays, material stockers and the interconnecting path, typically operates under control of a distributed computer system running a factory management program. Another program can be implemented to track and control the movement of material in the carriers throughout the plant. A typical semiconductor fabrication plant handles the processing of thousands of wafers at any given time. The wafers are typically divided into lots that undergo different processing sequences. Most of the time the mix of material, in the form of lots, moving through the plant includes test wafers and empty cassettes that need to move into and out of the manufacturing sequence. A more detailed discussion of the movement of lots throughout a semiconductor manufacturing facility may be found in U.S. Pat. No. 5,751,581 issued May 12, 1998 to Tau et al., entitled xe2x80x9cMaterial Movement Server,xe2x80x9d which is herein incorporated by reference.
When external factors force changes in the production schedule, substantial manual intervention is required to adjust the scheduled production of wafers and the movement of other material in the plant. Issues such as design/material changes, line balancing, quality control, sudden increase/decrease in demand of product, change in priority of wafer lots, or other management driven initiatives need to be integrated into the manufacturing process. However, the necessary adjustments to the production line and material movement are not readily known and usually require a substantial amount of time to execute. In view of the above, there is a need to integrate such events or integrate a high management level instruction into the production schedule without substantially disrupting the flow of material through the plant or lowering the manufacturing yield.
The present invention is directed to addressing the above, and other needs in connection with improving efficiencies of material lot movement and material processing in a semiconductor processing line.
Semiconductor fabrication facilities have material handling systems that manage production/test wafers as well as empty cassettes and carriers throughout the system. Changes to these systems have been manually coordinated by the operators on the line, which has led to delays in the system in processing the wafers or inefficiencies in manufacturing. It has been discovered that delays caused by event changes in the line or management initiatives external to the line can be reduced by integrating an appropriate business rules module into the manufacturing process. The module and system is capable of giving advanced notice of: a downstream opportunity for using manufacturing capacity that becomes available or an opportunity to reduce cycle time by rescheduling tool/equipment maintenance for a time when the line is not at its limit of capacity.
According to one aspect of the invention, a method of managing the movement of material lots through a processing facility includes tracking the movement of the material lots in the facility. The material lots are then rearranged in a material handling system as a function of a carrier code and an externally provided directive indicating a material lot movement sequence change.
According to another aspect of the invention, a method of managing the movement of material lots through a semiconductor fabrication facility includes tracking the movement of the material lots in the facility. A business rules module arrangement is accessed that generates material movement directives as a function of event changes on the line. Any externally provided directives in the business rules module are reviewed that can change the movement of material lots in a material handling system. The material lots in the material handling system are then rearranged as a function of a carrier code and the directive indicating a material lot movement sequence change.
In yet another aspect of the invention, a system for managing the movement of material lots through a processing facility includes a tracking arrangement that tracks the movement of the material lots in the facility. The material lots are rearranged in a material handling system as a function of a carrier code and an externally provided directive indicating a material lot movement sequence change.
In yet another aspect of the invention, a system for managing the movement of material lots through a semiconductor fabrication includes a material handling system adapted to move and track the movement of material lots in the facility. A business rule module coupled to the material handling system is adapted to rearrange the material lots as a function of a carrier code and an externally provided directive indicating a material lot movement sequence change.